1. Field of the Invention
This disclosure relates to system, apparatus and method for restricting access to data.
2. Description of the Related Art
In secure systems such as conditional access television (CATV), access to some data needs to be restricted. For example, a set top box for use in CATV may store broadcast television data that should only be accessed by an authorised user who has made the appropriate payment to the broadcast service provider. Access of data by unauthorized persons such as hackers compromises the security of the system and should be prevented.
Unauthorized access to services such as CATV broadcasts is often prevented by encrypting any data to which access should be restricted. With systems utilising encryption schemes, a hacker may be able to access data from within the system, but is prevented from using the information contained in the data by virtue of the encryption. However, encryption schemes rely on the confidentiality of secret keys that are used to decrypt the data. If the identity of the relevant secret key becomes known, then the system is breached. Hackers may also devise other ways to circumvent the security of the system.
We have appreciated the need for a system in which unauthorized data access can be identified so that access to confidential data can be restricted, whether encrypted or unencrypted.